/* row */
.flex-row-start{
    display: flex;
    flex-flow: row nowrap;
    justify-content: flex-start;
    align-items: flex-start;
}

/* 取最高的元素作为统一高度 */
.flex-row-start-stretch{
    display: flex;
    flex-flow: row nowrap;
    justify-content: flex-start;
    align-items: stretch;
}




.flex-row-center{
    display: flex;
    flex-flow: column nowrap;
    justify-content: center;
    align-items: center;
}
.flex-row-space-between{
    display: flex;
    flex-flow: row nowrap;
    justify-content: space-between;
    align-items: center;
}
.flex-row-space-around{
    display: flex;
    flex-flow: row nowrap;
    justify-content: space-around;
    align-items: center;
}
.flex-row-start-space-around{
    display: flex;
    flex-flow: row nowrap;
    justify-content: space-around;
    align-items: flex-start;
}

/* column */
.flex-column-center{
    display: flex;
    flex-flow: column nowrap;
    justify-content:center;
    align-items: center;
}

.flex-column-start-space-evenly{
    display: flex;
    flex-flow: column nowrap;
    justify-content: space-evenly;
    align-items: flex-start;
}

